关键词: 磷石膏, 常压酸化法, 改性粒状硫酸钙, 聚氯乙烯, 力学性能

Abstract:

Granular-like CaSO₄（G-CaSO₄） was prepared from phosphogypsum by atmospheric acidification.The effect of the reaction temperature and time on the phase and morphology of G-CaSO₄ were investigated by X-ray diffraction（XRD） and scanning electron microscopy（SEM）.Fourier transform infrared spectroscopy（FT-IR） and transmission electron microscopy（TEM，HR-TEM） analyses were performed on G-CaSO₄ of optimal conditions.Then，G-CaSO₄ was modified with stearic acid to obtain modified granular-like CaSO₄ （MG-CaSO₄），which was used as filler in PVC.The effect of MG-CaSO₄ on the micromorphology and mechanical properties of PVC composites were also studied.The results showed that the optimal conditions for the preparation of MG-CaSO₄ were as follows:the reaction temperature was 100 ℃ and the reaction time was 4 h.Under these conditions，G-CaSO₄ with an average particle size of 0.27 μm was successfully prepared，and then modified with 5%（mass fraction） stearic acid to MG-CaSO₄.MG-CaSO₄ was applied to PVC as filler，when the addition amount was 2%，the tensile strength，elongation at break and flexural strength of PVC composites were increased by 11.39%，41.73% and 14.02%，respectively.The research results ccould provide reference for the high-value utilization of phosphogypsum.

Key words: phosphogypsum, atmospheric acidification method, modified granular-like CaSO₄, polyvinyl chloride, mechanical properties